Harry A. J. Hoitink, Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio; Carol A. Musselman and Terry L. Moore, Research Assistants, Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University; Leona E. Horst, Research Assistant; Charles R. Krause, Adjunct Associate Professor, U.S. Department of Agriculture, Agricultural Research Service, Application Technology Research Unit, Wooster, Ohio; Randy A. Zondag, Ohio State University Extension, Chair and Extension Agent, Lake County, Painesville, Ohio; and Hannah Mathers, Assistant Professor, The Ohio State University, Department of Horticulture and Crop Science, Columbus, Ohio.
Composted dairy and swine manures incorporated into container media served as effective substitutes for similar products such as composted biosolids used more widely in Ohio nurseries. One single batch of composted cow manure tested in this work naturally suppressed the severity of a foliar disease. However, several other batches of composts that were tested did not provide control of foliar diseases even though they suppressed root rots. In cooperating nurseries where wet weather conditions occurred for a week or longer and where disease pressures were high for that reason and foliar diseases developed, inoculation of these container media at potting with T382 significantly reduced the severity of the foliar diseases and/or stem blights.
Finally, the sporadic occurrence of natural suppression of foliar diseases on plants produced in compost-amended media agrees with earlier laboratory studies which showed that the nursery industry cannot rely on natural composts for control of foliar diseases. The effect of T382 was promising and requires further analysis.